comsol multiphysics - didatticaweb

Comsol Multiphysics

Anno Accademico 2018/2019

Cristina Falcinelli, PhD

COMSOL Multiphysics• Almost all physical phenomena can be described by partial differential equations (PDEs)

• In general, almost all cases fall into the class that has “non-trivial” or “non-analytical” solutions

• Then numerical methods as Finite Element (FE) method are necessary to solve the problem

Powerful interactive environment for modeling and solving all kinds of scientific and engineering problems based on partial differential equations through FE analysis

COMSOL

COMSOL Multiphysics

FE method uses discretization (nodes and elements) to model the domain: the problem system is subdivided into small components called elements and the elements are comprised of nodes MESHING

Finite ElementsNodal Points

COMSOL Multiphysics

Finite Elements

Nodal Points

1D ElementsLine

2D ElementsTriangular, Quadrilateral

Plates, Shells

3D ElementsTetrahedral, Rectangular

Prism (Brick)

COMSOL Multiphysics

Finite Elements

Nodal Points

• Assign nodes to each element and then choose the interpolation function to represent the variation of the variable over the element.

• Obtain a set of algebraic equations to solve for unknown (first) nodal quantity (displacement).

• Secondary quantities (stresses and strains) are expressed in terms of nodal values of primary quantity

Features:

COMSOL Multiphysics

Finite Elements

Nodal Points

Different fields of application:

The COMSOL Multiphysics approach

Fluid Flow

Chemical Reactions

Acoustics

Electromagnetic Fields

Heat Transfer

Structural Mechanics

User Defined Equations

The COMSOL Multiphysics

Tips and useful informations:

• English

• LiveLink for Matlab

• Unit of measure

• Help


Model Wizard(Creatore Modelli)

or Blank Model(Modello Vuoto)


Model Wizard or Blank Model


Select Space Dimension


Select Physics e.g. StructuralMechanics


Select Physics e.g. StructuralMechanics Solid Mechanics ADD


Study


e.g. Stationary

Done


Model Wizard or Blank Model


Add Component1D, 2D, 3D

AddPhysics

AddStudy


Recovery file


Documentation


Documentation

Searchexpression


ApplicationLibraries


ApplicationLibraries

Open ApplicationOpen PDF Document


Model Builder: The model tree gives an overview of the model and all

the functionality and operations needed for building and solving a modelas well as processing the results




Definitions

Parameters




Geometry

The geometry can becreated or imported

The COMSOL MultiphysicsMaterial



The COMSOL MultiphysicsPhysics



The COMSOL MultiphysicsMesh

Physics-controlledmesh



Extremely fineExtra fineFinerFineNormal….

The COMSOL MultiphysicsMesh

User-controlledmesh



SizeFree Tetrahedral

The COMSOL MultiphysicsSolve

Compute



The COMSOL MultiphysicsResults



Post-processing


Settings Window: click any node in the model tree to see itsassociated settings window displayed next to the Model Builder


Settings Window: click any node in the model tree to see itsassociated settings window displayed next to the Model Builder

WidthDepthHeight


Graphics Window: The graphics window presents interactive graphics

for the geometry, mesh and results. Operations include rotating, panning, zooming and selecting


How to set up and run a simulation with Comsol Multiphysics?

Simulation workflow:

• Set up model environment

• Create geometrical objects

• Specify material properties

• Define physics boundary conditions

• Create the mesh

• Run the simulation

• Postprocess the results


Let’s start with an example!


1) Cubetto di materiale elastico lineare isotropo a cui applichiamo un campo di deformazioni (homogeneous strain BC) misuriamo le

tensioni generate. Per definire un materiale elastico lineare isotropo servono solo due costanti materiali E e ν (E=12 GPa, ν=0.32)

In elasticità lineare:

Matrice di rigidezza (6X6) Matrice di cedevolezza (6X6)

Se il materiale non possiede simmetrie costitutive (materiale anisotropo), le due matrici hanno 21 costanti elastiche indipendenti nel caso di materiale isotropo le costanti elastiche indipendenti si riducono a 2


1) Cubetto di materiale elastico lineare ortotropo a cui applichiamo un campo di deformazioni (homogeneous strain BC) misuriamo le

tensioni generate. Materiale ortotropo: esistono 3 piani di simmetria ortogonali tra loro.

In elasticità lineare:

Matrice di rigidezza (6X6) Matrice di cedevolezza (6X6)

Se il materiale non possiede simmetrie costitutive (materiale anisotropo), le due matrici hanno 21 costanti elastiche indipendenti nel caso di materiale ortotropo le costanti elastiche indipendenti si riducono a 9

comsol multiphysics - didatticaweb

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